Center mode control circuit

Abstract

A center mode control circuit includes an amplifying portion (31) for amplifying a center input signal, a switch (34) connected to an input terminal of the amplifying portion, and capacitors (35, 36) selected by the switch and having different characteristic from each other. The modes that are switched are (a) a normal mode for adding a low frequency component of the center input signal to left and right input signals, (b) a phantom mode for adding a full range of the center input signal to the left and the right stereo input signals, and (c) a wide mode for not adding the center input signal to the left and the right stereo input signals.

What is claimed is: 
     
       1. A center mode control circuit for switching of a normal mode for adding a low frequency component of a center input signal to left and right stereo input signals, a phantom mode for adding a full range of said center input signal to said left and right stereo input signals, and a wide mode for not adding said center input signal to said right and left stereo input signals, the center mode control circuit comprising: amplifying means for amplifying said center input signal;   switching means connected to an input terminal of said amplifying means for switching a mode of said control circuit to at least one of the normal, phantom and wide modes, and   first and second capacitor means selected by said switching means and having different characteristics from each other.   
     
     
       2. A center mode control circuit according to claim 1, wherein said amplifying means includes positive and negative input terminals and an output terminal, and   said switching means connected to the positive input terminal of said amplifying means, for switching a state of said positive input terminal via said first and second capacitor means to be at least one of open, connected to a high pass capacitor of said first capacitor means and connected to a full pass capacitor of said second capacitor means.   
     
     
       3. A center mode control circuit according to claim 1, wherein at least said amplifying means and said first and second capacitor means are formed in a single integrated circuit, and said switching means is connected to an external pin of said integrated circuit.   
     
     
       4. A center mode control circuit comprising: a first signal path for a left stereo input signal,   a second signal path for a center signal,   a third signal path for a right stereo input signal,   a high pass inversion amplifier means connected to said second signal path;   first adder means for adding an input signal and an output signal of said high pass inversion amplifier means to said left stereo input signal applied to said first signal path;   a second adder means for adding the input signal and the output signal of said high pass inversion amplifier means to said right stereo input signal applied to said third signal path; and   switching means for switching so that the output signal of said high pass inversion means becomes at least one of a high pass signal, a full range signal and a zero signal of said center signal.   
     
     
       5. A center mode control circuit according to claim 4, wherein said center mode control circuit is formed in a single integrated circuit, and said switching means is connected to an external pin of said integrated circuit.